Process for the separation and recovery of metals from metal alloys



Patented Sept. 5, 1922.

UNITED STATES PATENT OFFICE.

comm-0mm JUSTINE KROLL, or tuxnmnoao, tuxnmnuao.

PBO CESS FOR THE SEPARATION AND RECOVERY OF METALS FROM METAL ALLOYS.

No Drawing.

To all whom it may concern:

Be it knownthat I, GUILLAUME Jos'rmn KROLL, metallurgical engineer, asubject of the Grand Duchess of Luxemburg, residing at RueSchmilz-Hollerich 52, Luxemburg, Grand Duchy of Luxemb'urg, haveinvented certain new and useful Improvements in Processes for theSeparation and Recovery of Metals from Metal Alloys, of which thefollowing is a specification.

The present mventlon relates a process for the purpose of separatingindividual constituents from metal alloys (including impure metals) inorder either to free the metal alloys from the injurious metallicconstituents contained therein, or to recover the eliminatedconstituents.

T he invention is based on the observation that when alkaline-earthmetals (including magnesium) are introduced into fused metal alloys theycombine with certain metals of the alloy under treatment to form alloysor other compounds or mixtures which, inasmuch as they have a differentfusing point and a different specific gravity from the remaining part ofthe alloy under treatment, can be easily separated. from the latter byknown methods.

Accordingly,- the present invention consists in introducingalkaline-earth metals, or alloys (mixtures) of said metals betweenthemselves or with other metals. into the fused metal alloys undertreatment. The separable alloys or other compounds or mixtures abovementioned are thereby formed within the metal'alloys, and separate fromthe remaining part of the metal alloy under treatment by Stratificationeither immediately or after cooling; or if they remain distributedthroughout the mass of the metal, they may be separated out by one ormore segregation or liquation processes or, by crystallization orotherwise.

To mention a few examples, it is possible to separate antimony, bismuth,arsenic, tellurium (in a less easy manner, also tin, copper, zinc andthe noble metals) from lead alloys, by introducing sodium, calcium,strontium, barium or ma nesium. Antimony, arsenic and bismuth, may beseparated from alloys of tin; antimony, arsenic, tin, and tellurium fromalloys which mainly contain bismuth; antimony and arsenic from alloys ofzinc in the same manner.

The choice of the alkaline-earth metal to Application filed September21, 1920. Serial No. 411,751.

be used depends on the kind of the metal alloy and on the constituentswhich have to be separated out therefrom. Calcium is, in general, themost efiicient alkali earth metal for carrying out the presentinvention.

The alkali metals and the rare eartlf metals act in a similar manner asthe alkali earth metals. It may be advantageous in the present method touse the alkali earth metals or the rare earth metals in combination withalkali metals. This can be eifec-ted by using an alloy (mixture) ofalkali earth metals and alkali metals or rare earth metals. It may alsobe, preferable to first cause the alkali earth metals or metal (such ascalcium) to act upon the metal alloy under treatment in order to removepart of the constituents to be se arated, and subsequently cause thealkali metals or metal (such as sodium) or the rare earth metals to actupon the remaining part of the metal alloy under treatment in order toremove the remaining constituents to be separated, or these subsequentoperations may be effected vice versa.

It is obvious that the alkaline-earth metal or alkali metal or rareearth metal may also be added to the metal alloy under treatment in anyother form, for example inthe form of an alloy, or they may beincorporated into the metal alloy under treatment by electrolysis or achemical rocess.

For carrying out the process it is, of course, unnecessary to add therequired amount of alkaline-earth metal (or alkali metal or rare earthmetal) in one portion; but the treatment may be effected in a series ofsuccessive working stages with successive, portions of the requiredamounts of alkaline-earth metals (or alkali or rare earth metals.) Inthese successive operations different alkali earth metals may be madeuse 0.26% of bismuth. This lead was treated with 0.3% calcium. A more orless solidified mass raised to the surface of the metal bath and wasskimmed ofl f The analysis of this mass showed 2.0% of bismuth, while inthe remaining lead the bismuth content was reduced to 0.049%.

What I claim as new and desire to secure *by Letters Pia-tent of theUnited States is:

1. The method of separating and recovering metallic constituents frommetal alloys (including impure metals), which comprises introducing analkali-earth metal (including magnesium) into said metal alloys, formingthereby a compound of the alkali-earth metal with the metallicconstituents to be separated, this compound having a diilerent meltingpoint from and a specific gravity not more than that of the main metal,and

eliminating this compound from the remaining part of the metal alloyunder treatment.

2. The method of separating and recovering metallic constituents frommetal alloys (including impure metals), which comprises introducing aplurality of alkali-earth metals (including magnesium) into said metalalloys, forming thereby a compound of the alkali earth metals with themetallic constituents to be separated, this compound having a difi'erentmelting point from and a specific gravity not more than that of the mainmetal, and eliminatin this compound from the remaining part 01? themetal alloy under treatment.

3. The method of separating and recovering metallic constituents frommetal alloys (including impure metals), which comprises introducing analloy (mixture) of one or more alkali-earth metals (including magnesium)with other metals into said metal alloy forming thereby a compound ofthe alkali earth metals with the metallic constituents to be separated,this compound having a different melting point from and a specificgravity not more than that of the main metal, and eliminating thiscompound from the remaining part of the metal alloy under treatment.

4. The method of separating and recovering metallic constituents frommetal alloys (including impure metals), which comprises introducingcalcium into said metal alloys,

forming thereby a compound of calcium with the metallic constituents'tobe separated, this compound having a different melting point froIn' andaspecific gravity not more than that of the main metal, and eliminatingthis compound from the remaining part of the metal alloy undertreatment.

5. The method of separating and recovering metallic impuritiesfromimpure lead, which comprises introducing calcium into the impure lead,forming thereby a compound of calicum and the metallic impurities to beseparated, this compound having a different melting point from and aspecific gravity not more than that of the main metal, and eliminatingsaid compound from the lead under treatment.

6. The method of separating and recovering bismuth from impure lead,which comprises introducing calcium into the impure ead, forming therebya compound of calcium and bismuth, this compound having a differentmelting point from and a specific gravity not more than that of the mainmetal, and eliminating said compound from the lead under treatment.

7. The method of separating and recovering bismuth from impure lead,which comprises introducing an alloy (mixture) of calcium with othermetals into the impure lead, forming thereby a compound of calcium andbismuth, this compound having a difierent melting point from and aspecific gravity not more than that of the main metal.

and eliminating said compound from the lead under treatment.

8. The method of separating and recovering metallic constituents frommetal alloys (including impure metals), which comprises introducing analloy (mixture) containing alkali-earth metals (including magnesium) andalkali metals into said metal alloy, forming thereby a compound of thealkali-earth metals and alkali metals with the metallic constituents tobe separated, this compound having a different melting point from and aspecific gravity not more than that of the main metal, and eliminatingthis compound from the remaining part of the metal alloy undertreatment.

9. The method of separating and recovering subse uently metallicconstituents from metal al oys- (including impure metals) whichcomprisesintroducing an alkali metal into said metal alloys, formingthereby a compound of the alkali metal with one or more of the metallicconstituents to be separated, eliminating this compound from theremaining part of the metal alloy under treatment, introducing analkali-earth metal (including;1 magnesium) into the remaining part of te metal alloy under treatment, forming thereby a compound of thealkaliearth metal with the remaining part of the metallic constituentsto be separated, and

Ill

10. The method of separating and recov-' ering subseguently metallicimpurities from impure lea WhlCll comprises introducing sodium into theimpure lead, forming thereby a compound of sodium with part of the ametallic impurities to be separated, eliminating this compound from theremaining part of the lead under treatment, introducing calcium intothis remaining part of the lead under treatment, forming thereby acompound of calcium with the remaining part of the metallic impuritiesto be separated, and eliminating this compound from the remaining partof the lead under treatment the compounds being eliminated havin adifierent melting point from and a speci e gravity not greater than thatof the main metal.

11. The method of separating and recovering metallic constituents frommetal alloys (including impure metals), which comprises introducing analloy (mixture) containing alkali-earth metals, (including magnesium)and rare earth metals into said metal alloy, forming thereby a compoundof the alkali-earth metals and rare earth metals with the metallicconstituents to be separated, and eliminating this com ound from theremaining part of the meta alloy under treatment.

12. The method of separating and recovering subsequently metallicconstituents from metal alloys (including impure metals) which comprisesintroducing an alkali-earth metal (including magnesium) into said metalalloys forming thereby a compound of the alkali-earth metal with one ormore of the metallic constituents to be separated, eliminating thiscompound from the remaining part of the metal alloy under treatment,introducing rare earth metals into the remaining part of the metal alloyunder treatment, forming thereb a compound of the rare earth metals withthe remaining part of the metallic constituents to be separated, andeliminating this compound from the remaining part of the metal alloyunder treatment.

13. The method of separating and recovering subsequently metallicimpurities from impure lead, wh1ch comprises introducing calcium intothe impure lead, forming thereby a compound of calcium with part of themetallic impurities to be separated, eliminating this compound from theremaining part of the lead under treatment, introducing rare earthmetals into this remainin part of the lead under treatment, forming tereby a compound of the rare earth metals with the remaining part of themetallic impurities to be separated, and eliminating this compoundfromthe remaining part of the lead under treatment.

In testimon whereof I afiix my signature in presence 0- two witnesses.

V. MULLER, R. HENPEN.

